Free-air unloader for compressors



Patented Dec. 20, 1927." a

. posed a piston C.

. discharge chamber F. In the construction NIT-ED, STA/TES- AT N orori;

JOHN LE VALLEY, OF PAINTED POST, NEW YORK, ASSIG NOR T0 INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY A CORPORATION OF NEW JERSEY."

FREE-AIR UNLOADER FOR (JOIMIIIPRESSORS.

Application filed January 12, 1927. Serial No. 160,858. 1

mission and exhaust of air into and fromthe compressor cylinder.

The objects of the invention are .to prevent, the up-building of a receiver pressure in excess of that which it'is desired to maintain for immediate purposes, and in general, to simplify the construction and reduce the costs of manufacturing and maintaining devices of this character.

Other objects will be in part obvious'and in part pointed out hereinafter.

, The invention consists of the combination of elements and arrangement of parts having the general mode of o eration substantially as hereinafter descrlbed and claimed and illustrated in the accompanying drawing, in which The figure is a sectional elevation of a portion of the compressor cylinder having the invention applied thereto.

Referring more particularly to the drawing, A represents a compressor. cylinder having a piston chamber B in which is dis- Disposed on the end of the cylinder A is a head D having an inlet assage E through which air may be supp led to the iston chamber B and .also having a disc arge chamber F into which the air compressed by the piston C may be discharged.

In an inner wall G of the head D is formed an opening H to afford communication between the piston chamber B and the shown, agdischarge valve mechanism J comprising theusual valve seat K, valve plate .L and stbp plate 0 is seated in the opening H to control communication-between the'sa-id chambers B and F. The valve mechanism J is held firmly in assembled position by a jack screw P screwed through a cover Q which forms a closure. for the'discharge chamber F. i

The air discharged into the discharge chamber F may pass therefrom through a port R in the head D and thence through a suitable conduit S ,to a receiver tank T of any suitable type.

the mechanism 6 is unseated, the outer end According to, the present invention a hole U in the wall G which affords communication between the piston chamber B and the inlet passage E comprises an enlarged porti6n Vg.and a portion of smaller, diameter W oined in thlSlIlStfl-IICG by a tapered surface or seat X adapted to cooperate with a similarly tapered surface Y of the seat Z a of an inlet plate valve mechanism 1). In

addition to the seat Z the inlet plate valve mechanism 1) also. comprises a stop plate a and a valve plated clamped operatively be- The enlarged portion or diameter V .of the opening U is preferably of considerably larger diameter than the valve seat Z so that when the said valve assembly 6 is moved from its normal operative position in a manner to be more fully described hereinafter, a suitable and adequate space will ex ist between the valve seat Z and the wall of the opening U to permit the free passage of sition it is intended to occupy while the compressor is operating under fullload conditions; To this end an unloader stem 0 'is disposed slidably through an end wallf ofthe head D and has a reduced portion 9 which extends through the valve seat Z and the valve plate 65 and is screw threaded at its inner end to receive the sto plate 0. The outer, or what may be terme the free end it of the unloader stem e is in this instance provided with an annular external groove [for the reception of a slotted wash-' er I: which serves as a' sea't'for one end of a coil-spring o interposed between the said washer is and the wall 7 ofthe head D for holding the valve seat Z firmly against the tapered seat X in the opening U.

In the present instance a guide 1) is dievtween the valve seat Z and said stop plate.

posed in the wall 7 of the head D to act as a guide for the stem 6. A portion q of the guide 77 which projects rearwardly of thehead D is preferably of such diameter as toform aguide for the spring 0 and of such length as toextend within a suitable distance of the washer is. In this way when I of the body r'is exteriorly threaded as at t for the reception of a corres ondingly threaded cap u between which an the body r is clamped a rubber diaphragm 'v to span the end of the body 1'. in the present instance is supported by and is adapted to act against a diaphragm head 10 supported by the washer is. Preferably, a pressure chamber :20 is formed in the inner face of the cap a forthe reception of pressure fluid to act against the diaphragm 1:.

Pressure fluidis in this instance cons veyed to the pressure chamber m through a pipe 3 leading from the receiver tank T to the ressure chamber wherewith 'it commumcates through a passage 2 in the cap e. Any suitable and well known means may be provided for controlling the admission of pressure fluid from the receiver tank T into the ressure chamber w whenever it is desire to unload the compressor, or in other words, Whenever the pressure in the receiver tank T exceeds a value which it may be desirable to maintain. In the drawing, a pressure controlling valve 2 is interposed in the pipe y for this purpose. The pressure controlling valve 2 is preferably of the type described in United States Patent No. 1,138,278, granted May 4, 1915 to J. H. Castle and We G. Rogers to which patent reference may be had for a detail description of the construction and operation of .the valve illustrated. The invention, however, is not de endent for its successful op-' eration upon t e precise type of controlling valve disclosed and other suitable and well known devices may be substituted for the valve 2 for controlling the admission of pressure fluid'to the pressure chamber w.

During the period that the compressor is operating under full load conditions, the instrength to hold t .let valve mechanism will occupythe posi-- jected during the normal 0 ration of the" compressor. The air thus rawn into the piston chamber B will then be compressed by the piston C as is of course understood,

The diaphragm '0.

and is discharged through the discharge valve J into the discharge chamber F, thence through the port R and through the conduit S into the receiver tank T. The operation described may continue indefinitely so long as the pressure in the receiver tank T'does not exceed a certainpredetermined value. In the event, however, that the pressure in the receiver tank T should exceed that which it is desired to maintain or at which the pressure regulating valve 2 is adjusted to open, the said valve 2 willestablish communication between the receiver tank T and the pressure chamber m to allow pressure fluid to act against the diaphragm 2). Upon the introduction of pressure fluid into the pressure chamber m the diaphragm Q) will act against the diaphragm head w and compressing the spring 0 will move the valve assembly 6 in the direction of the piston chamber B, thus establishing a free. passage over and around the tapered portion Y of the valve seat Z between the inlet passage E and the piston chamber B.

As will be observed the air will be pumped back and forth between the inletpassage E and the piston chamber B without necessitating the operation of the valve plate at and wlthout discharging any air i into the discharge chamber F. The compressor may continue to operate under these conditions until the receiver pressure has the exhaust of pressure fluid from the pressure chamber as, the spring 0 will again react to return the valve mechanism b to its normal operative position.

I claim: I

1. In a compressor, the combination of a cylinder, a head for the cylinder having an inlet passage, said head also having an opening to afi'ord communication between the cylinder and .the inlet passage, a valve mechanism seated in the opening to control the opening, a stem reciprocable in the head supporting the valve mechanism, a spring acting against the stem for holding the valve mechanism in normal operative position, andpressure responsive means associated with the stem for actuating the valve mechanism bodily inward towards the cylin- .der space and out of operative position to permit free and uninterrupted communication around-the valve mechanism between the inlet passage and the cylinder.

2. In a compressor, the combination of a cylinder, 9. head for the cylinder having an inlet passage, said head also having arropening to afford communication between .the cylinder and the inlet passage, a seatin the opening, a valve mechanism adapted to rest on the seat, a stem in the head supporting application I eeann the stem'to hold the va' ve" mechanism against the seat during the loaded perlod of the compressor, anunlo'ader bed on the head, a cap for the unloader b0 y, and a diaphragm clamped between the body and the cap actin against the stem u on the preesure fluid te t 9 dia-' L the valve inechanism, a spi'in acting a gainst "pln'agm 'far unseatin an an inwardly direction; thus establishing uninterrupted cqmmunicatiom between the cylinder and the" inlet passage." testimony whereof I have signed this specification 4 IJ'OI'INLE VA LEY. P 

